The purpose of these studies is to investigate the effects of varying degrees of severity of diabetes mellitus on adrenal glucocorticoid production during pregnancy in rabbits. These studies will be performed on maternal and fetal tissues beginning at about the midterm of pregnancy and extending to the immediate postpartum period. Specifically to be studied are: 1) the plasma levels of the adrenal glucocorticoids cortisol and corticosterone and free fatty acids and glucose; 2) the in vitro production of cortisol and corticosterone during incubation of the adrenals in the presence and absence of insulin and/or ACTH; 3) the effect of insulin therapy during pregnancy on plasma levels and in vitro production of glucocorticoids. Adrenal steroid levels will be measured by radioimmunoassay.